Isolation and characterization of MOD5, a gene required for isopentenylation of cytoplasmic and mitochondrial tRNAs of Saccharomyces cerevisiae

Mol Cell Biol. 1987 Jan;7(1):177-84. doi: 10.1128/mcb.7.1.177-184.1987.


The mod5-1 mutation is a nuclear mutation in Saccharomyces cerevisiae that reduces the biosynthesis of N6-(delta 2-isopentenyl)adenosine in both cytoplasmic and mitochondrial tRNAs to less than 1.5% of wild-type levels. The tRNA modification enzyme, delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase, cannot be detected in vitro with extracts from mod5-1 cells. A characterization of the MOD5 gene would help to determine how the same enzyme activity in different cellular compartments can be abolished by a single nuclear mutation. To that end we have cloned the MOD5 gene and shown that it restores delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase activity and N6-(delta 2-isopentenyl)adenosine to tRNA in both the mitochondria and the nucleus/cytoplasm compartments of mod5-1 yeast cells. That MOD5 sequences are expressed in Escherichia coli and can complement an N6-(delta 2-isopentenyl)-2-methylthioadenosine-deficient E. coli mutant leads us to conclude that MOD5 is the structural gene for delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkyl and Aryl Transferases*
  • Cytoplasm / metabolism
  • DNA Restriction Enzymes
  • Genes*
  • Genes, Fungal*
  • Genetic Complementation Test
  • Mitochondria / metabolism
  • RNA, Transfer / genetics*
  • RNA, Transfer / metabolism
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins
  • Transferases / genetics*


  • Saccharomyces cerevisiae Proteins
  • RNA, Transfer
  • Transferases
  • Alkyl and Aryl Transferases
  • MOD5 protein, S cerevisiae
  • tRNA isopentenyltransferase
  • DNA Restriction Enzymes